This invention relates to a mounting assembly comprising an electronic module and a rack for receiving the module, and to an electronic module.
The increased use of electronic components such as electronic chips and integrated circuits mounted on printed circuit boards, or otherwise, has led to pressure to reduce the space which is occupied by the components and their associated mounting assemblies. Components which are packaged as printed circuit boards, or otherwise, are therefore often mounted in a rack, either directly as an electronic module, or positioned on a chassis which for present purposes will be considered as an electronic module, whether or not electronic components are present on the chassis. The use of electronic modules mounted in racks has the advantage of convenience during the assembly and maintenance of equipment.
Reduction in the space occupied by electronic modules has resulted in an increase in the density of contacts for connection to the modules. The reduction in space has also resulted in a need to be able to dissipate heat from the module because of the higher density of heat emitting components. This is often achieved by mounting the modules in thermal contact with a heat sink, for example a rack of a thermally conductive material such as aluminum.
In order to be able to maintain equipment which incorporates electronic modules in full working order, it is desirable to be able to remove and to replace the modules, and therefore to be able to release the modules from the contact pins and the mounting rack in which they are located when in use. Known fasteners for ensuring that the contacts on a module and its corresponding rack are engaged include a manually operated lever mounted on the module which engages a recess in the rack. This system suffers from the disadvantage however that is requires the operator to exercise skill in inserting the module in the rack, and to exert sufficient force to ensure proper engagement, but not so much force that the contacts on the module or the rack (or both), which can often be delicate, are damaged. Furthermore, there are often many connections between the module and the rack, and when these are formed as pins and sockets, the operator can often be required to exert considerable force to ensure proper engagement.
It is known also to make a heat sink link between a module and the rack in which it is mounted by means of a plurality of wedges located between the module and the rack which can be made to move towards one another by a screw so as to increase the effective depth of the wedges, thereby forcing the module against the rack. A torque limiter may be used to ensure that the required torque is applied to the wedges and is not exceeded.
A discussion of fastening devices for electronic modules is contained in Machine Design, 8th January 1987, pages 115 to 118.